Combustion Reactions | Chemistry for EmSAT Achieve PDF Download

What are Combustion Reactions?

A combustion reaction is a chemical process where a fuel undergoes oxidation by interacting with an oxidizing agent, leading to the liberation of energy, typically in the form of heat.

Combustion Reaction Explanation

• Combustion reactions typically involve highly exothermic redox reactions between an oxidizing agent and a fuel. The resulting product of a combustion reaction is usually the oxidized fuel, often emitted in the gaseous state, commonly referred to as smoke. Flames frequently accompany combustion reactions, though it's important to recognize that not all of them lead to fires.
• Solid fuels such as coal and wood initially undergo endothermal pyrolysis, producing gaseous fuels. The combustion of these gaseous fuels generates the heat necessary to sustain further combustion. Additionally, combustion reactions can produce enough heat to generate incandescent light, typically in the form of flames or flickering.
• A straightforward example of combustion is the transformation of hydrogen and oxygen into water vapor, a process commonly employed to power rocket engines. In this reaction, hydrogen acts as the fuel while oxygen serves as the oxidizing agent. This combustion reaction releases more than 242 kilojoules of heat per mole of fuel combusted.

Examples of Combustion Reactions in our Day-to-Day Lives

Below are everyday examples of combustion reactions commonly encountered by people:

• When cooking food on gas stoves using LPG fuel, a combustion reaction occurs between the oxygen in the air and the liquefied petroleum gas.
• The engines of cars, motorcycles, and other fossil-fuel-powered vehicles derive their power from the combustion reaction between petrol (or diesel) and oxygen.
• Matchsticks ignite through a combustion reaction. Striking a matchstick against a rough surface heats up the red phosphorus at the tip, initiating a combustion reaction between the phosphorus and atmospheric oxygen.
• Fireworks explosions result from combustion reactions. Specific ions are added to the fuel to produce different flame colors in these redox reactions.
• Various other combustion reactions are utilized across a wide range of industries. For instance, the space industry utilizes the combustion reaction between hydrogen and oxygen to generate clean energy in rocket propulsion systems.

Chemical Equations of Important Combustion Reactions

The combustion of methanol (sometimes referred to as ‘wood alcohol’) involves a chemical reaction between methanol and oxygen. The chemical equation for this reaction is given by:
2CH₃OH + 3O₂ → 4H₂O + 2CO₂
The combustion reactions undergone by methane are also known to yield water and carbon dioxide as products. This reaction can be represented by the following chemical equation:
CH₄ + 2O₂ → 2H₂O + CO₂
The combustion of propane, which is widely employed in cooking setups like fire grills, is represented by the following chemical equation:
2C₃H₈ + 7O₂ → 8H₂O + 6CO₂
Another important combustion reaction involving the oxidation of a hydrocarbon is the combustion of ethane. The chemical equation for the reaction between ethane and oxygen that yields carbon dioxide and water is provided below.
2C₂H₆ + 7O₂ → 6H₂O + 4CO₂
Naphthalene also undergoes combustion in the presence of oxygen to afford carbon dioxide gas and water. The chemical equation for this reaction is given by:
12O₂ + C₁₀H₈ → 4H₂O + 10CO₂